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Assembly in Action: Manufacturer Cuts Process Time With Adhesive Dispensers

Helwig Carbon Products Inc. (Milwaukee) designs and manufactures carbon brushes for electric motors. Its carbon brushes are used in small, fractional horsepower motors, as well as huge overhead cranes and power stations.

The company’s Red Top line features an innovation that reduces vibration and extends brush life. The Red Top product line has a special top that consists of a composite wafer bonded to a rubber base. Depending on product size and configuration, the top is attached to the brush with a dot or stripe of room temperature vulcanizing adhesive.

Until recently, workers applied the adhesive from 6-ounce cartridges loaded into pneumatic dispensing guns. The amount of adhesive applied was controlled by how long the operator held the trigger. Even though this method got the job done, it was impossible for workers to apply a uniform deposit on every part. The variations in the adhesive amounts had a negative effect on overall process time, according to Mahesh Kestursatya, materials engineer at Helwig.

When too much adhesive was applied, it would ooze onto the front and sides of the brush as the top was pressed in place. The excess had to be scraped off with a razor blade. This was a tedious, time-consuming process that slowed down the workflow. And because Helwig runs their brushes through an oven to speed curing, larger-than-necessary adhesive deposits resulted in longer cure times.

The company searched for a more efficient dispensing process. It found the answer at Assembly Technology Expo in Rosemont, IL. The answer proved to be EFD Inc.’s (East Providence, RI) UltraSaver dispenser.

UltraSaver is a compact tabletop dispensing unit that uses controlled air pressure and a precision timer to dispense adhesives in consistent, repeatable amounts. The adhesive is applied from a disposable syringe reservoir connected to the dispenser control unit by a lightweight air line. The syringe is fitted with a special piston that improves fluid control and wipes the syringe interior clean as fluid is dispensed. A general-purpose or special-purpose dispensing tip threaded onto the front of the syringe simplifies application of fluids with different viscosities and characteristics.

With the power cord connected and air pressure adjusted to move the fluid at a steady rate, the operator places the dispense tip in position and taps an electric foot switch to initiate the dispensing cycle. The timer is used to make uniform dots or fill cavities with material. When neat, controlled stripes are needed, the timer is turned off, and the operator starts and stops the dispense cycle with the foot pedal.

Impressed by the dispenser’s potential, one was ordered for evaluation on Helwig’s
production floor. “It looked like a better application method,” says Kestursatya, “but we had to make be sure our employees would be happy with it. If they weren’t, it wasn’t going do us any good.”

When the dispensing unit was set up, some workers readily accepted it. Others wanted to stay with the air guns. However, once they saw the results their colleagues achieved, they quickly abandoned the old tools. Helwig soon had four more dispensers on the shop floor.

Their new dispensing method has brought Helwig several benefits, including faster workflow, lower adhesive costs and higher production capacity.

“Workflow has improved considerably,” says Kestursatya. “With the air guns, we always had a lot of rework. With the EFD systems, we’ve cut parts cleaning by almost 85 percent. We just apply the dot or stripe, inspect it and send the part on to the next process.”

Cure time has been dramatically reduced
as well. Curing used to take between 2 and 2.5 hours, depending on the size of the brush. Now that Helwig has a reliable way to put the same amount of adhesive on every part, cure time has decreased to 45 minutes or an hour at most, which increases process speed as much as
70 percent.

In addition, the company estimates their adhesive use has declined almost 60 percent. With the air guns, an operator consumed between three and five 6-ounce cartridges of adhesive during a shift. Now adhesive use has dropped to just one or two cartridges per operator.

The dispensers have also improved the company’s ability to respond to rush orders. “It’s very common for us to get a last-minute order from a customer who needs it shipped by the end of the day,” says Kestursatya. “Because we can’t speed up the process beyond a certain point, being able to eliminate the cleaning step and cure parts much faster has really been a big help. By recording the dispenser settings used for a particular product, we can be sure of producing identical results any time that job is run.”

“The greatest thing about these dispensers is that the results are not operator-specific,” he concludes. “It doesn’t matter who is performing an operation. Once the dispenser settings are locked in, the results are going to be consistent. No matter who is working on an order, it always comes out the same.”

For more information on dispensers, call 800-556-3484 or visit www.efd-inc.com.